Advancements in communication technologies have permitted the implementation, and widespread usage, of multi-user radio communication systems. A cellular communication system is exemplary of such a radio communication system. Information signals generated during operation of the radio communication system are transmitted upon radio communication channels defined upon portions of the electromagnetic spectrum. Regulatory bodies allocate portions of the electromagnetic spectrum for communications in various communication systems.
To convert the information signal into a form to permit its communication upon a communication channel defined in a radio communication system, a transmitting station modulates the information signal upon a carrier wave of a carrier frequency within the range of frequencies which defines, at least in part, the communication channel. Through such modulation process, a base band-level signal of which the information signal is formed is converted into a radio frequency signal of desired frequency characteristics.
A transmitter, operable to transmit radio frequency signals upon a radio channel, typically includes one or more up-mixing stages at which the base band information signal is up-converted in frequency to be of the selected radio frequency. The mixing stages include mixer circuits coupled to receive the information signal and an up-mixing signal with which the information signal is to be multiplied, or otherwise combined to form an up-converted signal. When multiple mixing stages are utilized, an IF (intermediate frequency) signal is formed at a first, or first series of, mixer stages. A radio frequency signal is formed at the final mixing stage.
A receiver which receives a radio-frequency communication signal transmitted thereto upon a radio communication channel must, analogously, convert the radio frequency signal to a base band level. One or more down-conversion stages is utilized to down-convert the radio frequency signal to a base band-level.
Both the transmitter and the receiver include, typically, an antenna transducer. The antenna transducer, when coupled to a transmitter to form a portion thereof, transduces the radio frequency signal generated at the transmitter out of electrical form and into electromagnetic form for transmission upon the radio channel. The antenna transducer, when coupled to a receiver to form a portion thereof, conversely, transduces radio frequency signals out of electromagnetic form and into electrical form for processing by the circuitry of the receiver.
A radio transceiver, having both a transmitter and a receiver to permit two-way communications, sometimes utilizes an antenna transducer which is shared by both the receiver and transmitter portions of the transceiver. A filter duplexer is sometimes utilized if the radio transceiver is operable pursuant to a frequency division multiplexing scheme having separate transmit and receive pass bands.
Antenna transducers coupled to radio transmitters, receivers, or transceivers are constructed to be caused to exhibit selected antenna patterns which are representative of antenna gain characteristics. Such antenna patterns typically include one or more antenna lobes which form omnidirectional or highly-directional antenna patterns. Selection of the configuration of the one or more antenna lobes is made to best facilitate transmission or reception, as appropriate, of the radio frequency signals communicated during operation of the device to which the antenna transducer is coupled.
In a cellular communication system in which portable, mobile phones are utilized by a user to effectuate telephonic communications, both power and size considerations are significant factors which make difficult antenna design for such mobile phones. And, because mobile phones are typically constructed to be operated in manners analogous to that by which a conventional, telephonic handset is positioned, portions of the antenna pattern exhibited by the antenna transducer of the mobile phone is positioned upon a portion of the user's body. Such overlapping is unproductive use of the energy which defines the antenna pattern.
If a manner could be provided by which to shift the antenna pattern exhibited by the antenna transducer so that an increased portion of the energy which defines the antenna pattern would be available for transceiving communication signals, improved radio performance would result.
It is in light of this background information related to antenna apparatus that the significant improvements of the present invention have evolved.